Implantable medical leads are devices that deliver electrical signals to implantable medical devices. Exemplary implantable devices are cardiac rhythm management (CRM) systems (e.g., pacemakers, defibrillators, and cardiac resynchronization therapy devices) and neurostimulation systems (e.g., spinal cord stimulation (SCS) systems). For CRM systems, medical leads are typically advanced intravascularly to an implant location within or on a patient's heart, while for neurostimulation systems, such leads are typically positioned beneath the skin, in vessels located in the neck or limbs, in the pectoral region, in the epidural space of the spinal cord, or intramuscularly.
Implantable leads typically include a flexible conductor surrounded by an insulating tube or shaft that extends from an electrode at the distal end to a connector terminal at the proximal end. Many leads incorporate multiple connectors extending from an electrical contact on a connector terminal to an electrode on a distal end of the lead body. When the connector terminal is coupled to an implantable device, and the device and lead are implanted in a patient, certain stresses or strains may develop in portions of the lead body or conductors near the terminal connector, or regions of a lead that experience bending.